Photographic layers and process of manufacture thereof



Patented Sept. 5, 1944 UNITED PHOTOGRAPHIO LAYERS AND PROCESS OF MANUFACTURE THEREOF Fritz Jaif, Brussels-.Ixelles, Belgium, assignor,

by mesne assignments, to Chromogen, Incorporated, a corporation of Nevada No Drawing. Application July 18, 1939, Serial No. 285,189. In Great Britain Jilly 29, 1938 4 Claims.

This invention relates to the manufacture of photographic layers. Gelatin is generally used as the binding agent in the preparation of such photographic layers, but as gelatin is an animal product its qualities vary to a great extent and it is therefore difficult to obtain gelatin layers of uniform and always reproducible qualities. has alreadybeen proposed to replace the gelatin by artificial products; for instance, it has been proposed to employ as the binding agent'a cellulose acetate which is hydrolised'to such an extent that it becomes soluble in water or at least soluble in mixtures of organic solvents and water containing a considerable quantity of the latter. Cellulose acetate hydrolised to such an extent is, as is well known, not a uniform chemical compound but contains cellulose acetates ofdifierent Itv degree of acetylation and also acetates of byproducts resulting from partial destruction of the cellulose. Therefore, photographic layers produced from such cellulose acetates show the same disadvantages as gelatin layers. Furthermore, it has been proposed to replace the gelatin by water-soluble cellulose ethers such as methyl cellulose or hydroxy alkyl ethers of cellulose, and by water-soluble.condensation products such as, for instance, polyacrylic acids.

It has now been found that the gelatin can be replaced advantageously by such cellulose ethers as contain at least one free carboxylic or sulphonic acid group and which are water-soluble, or at least easily swell in water, without being previously hydrolised; also the water-soluble salts of such cellulose derivatives can be employed.

The present invention therefore relates to photographic materials containing special binding derivatives for the manufacture of the supports of photographic layers has already been described but not for the manufacture of the layers themselves.

Example 50 cos. of a 1.5% aqueoussol'ution of the sodium salt 01' cellulose glycollic acid are added to 50 cos. of a not specially sensitized silver bromide emul-' sion containing 10% gelatin. The whole is thoroughly mixed and coated onto a surface. of 0.2

square metre.

The light-sensitivity of the layer thus obtained .shows no difference compared with the lightadvisable to add wetting agents to the emulsion agents. The photographic material according to the present invention comprises binding agents, which, partly or entirely,'consist of carbohydrate ethers containing at least one free carboxylic or sulphonic acid group, or of water-soluble salts of such carbohydrate ethers.

For instance, cellulose acetic acid usually also referred to as cellulose glycollic acid or its sodium or ammonium salt is very suitable for this purpose. Furthermore the higher homologues of cellulose glycollic acid, such as cellulose propionic acid, and the corresponding derivatives of other carbohydrates such as starch, dextrines and similar compounds can be employed. Cellulose ether esters, as for instance, cellulose'acetate glycollic acid may also be used. Suitable cellulose derive tives containing sulphonic acid groups are, for instance, the compounds described in British Patent Specification No. 479,316. Compared with the cellulose ethers suggested for this purpose, such as methyl cellulose, these compounds have the advantage that they contain an acid group, an advantage which is especially useful in the forming of layers for color photographic purposes. The use of the above mentioned cellulose or to the binding agent solution.

The new binding agents can be employed in the same manner as gelatin, replacing the gelatin partly or entirely. The layers containing them can be colorless or colored and they may contain light-sensitive silver salts and if necessary, sensitizers. They are especially useful for employment in color photographic singleor multi-layer materials. The new layers can be hardened by the same methods hitherto used for the. hardening of the gelatin layers, for example, by employing formaldehyde as the hardening agent.

1. A photographic layer comprising a lightsensitive silver halide and a binding agent therefor comprising essentially a mixture of gelatin and a cellulose glycollic acid.

2. A photographic'layer comprising a, lightsensitive silver halide and a binding agent therefor comprised essentially of cellulose glycollic acid.

3. A photographic layer comprising a light-sensitive silver halide and a binding agent therefor comprising essentially at least one member selected from the group consisting of cellulose glycollic acid, water soluble salts of cellulose glycollic acid, cellulose propionic acid, cellulose acetate glycollic acid and mixtures of any of these with gelatin.

4. A photographic multilayer material comprising a pluralityof superposed layers on a common support, one of said layers comprising a lightsensitive silver halide and a binding agent therefor comprisingessentially at least one member selected from the group-consisting of cellulose glycollic acid, water soluble salts of cellulose glycollie acid, cellulose propionic acid, cellulose acetate glycollic acid and mixtures of any of these with gelatin.

r'arrz JAFFE. 

